TEKNOLOGI ARANG BATU – PART II - Universiti …mineral.eng.usm.my/web halaman mineral/coal...

EBS 425/3 -Mineral Perindustrian Fossil fuel (Coal)

Disedia oleh : Dr. Kamar Shah Ariffin ( 6/30/2003) Page 1 of 15

TEKNOLOGI ARANG BATU – PART II Coal Processing

Coal that is going to be burned in solid form may go through a variety of preparation processes. The simplest of these is removing foreign material and screening for size. Large pieces may be crushed, or the whole mass pulverized to a certain size. Coal can also be washed or cleaned to remove contaminants. It is also possible to turn solid coal into a gas or liquid fuel, but these are much more complex processes, sometimes called clean coal technologies. Coal that is going to be used in steel making is processed into coke.

Coal Transport Domestically, coal is moved primarily by barge and rail, although it may initially move by truck from the mine. In many cases it is transported long distances, for one of two reasons. First, a particular type of coal may be needed far from where it is found. Examples include coal with a low sulphur content that reduces sulfur dioxide emissions, and special coal used to make steel. Second, a lot of coal is burned to make electricity in places where no coal is found locally, so it has to be brought in. In addition, some coal is exported by ship, mostly for steel making in other countries

Calculate coal reserves for each coal bed:

This is the complicated part; most people would hire a registered consulting geologist or registered mining engineer for this. The process is explained here, in simplified terms. Each step is done separately for each of the coal beds under consideration. The first step is to gather as much coal thickness information as possible for the target coal bed. Information may be obtained from the Mineral and Geosciences department. Coal Thickness Data Base, and files of local coal companies, and neighbours and by examining outcrops, digging out the coal, and possibly drilling boreholes (drilling can be paid for by interested companies). After coal thickness data are gathered, a map showing coal thickness trends (isopach map) is constructed for the target bed. Property lines and the target coal-bed outcrop lines are added to the map. Next, the area for each thickness class must be measured (generally in acres). This process is called planimetry. Planimetry measures the area of the property. With the area and thickness known, a volume of coal can be calculated, and from this volume, a total tonnage can be derived. Planimetry can be done by hand using several methods, but the most accurate is with a mechanical device called a planimeter. Planimetry can also be done accurately by a computer using special software. From the calculated areas and the projected thickness trends, a gross reserve estimate can be calculated; for bituminous coal, there are 1,800 tons for every acre for every foot of coal (e.g., if you have 2 acres of 2-foot-thick coal, then you have 7,200 tons of that coal). Many other factors must also be examined to determine what the coal is worth: quality, mineability, transportation, available market, etc.



ENERGY SOURCES

Important properties and Use of Coal

The chief uses of coal mined in the world are electricity generation, heat, and coking coal for iron and steel making. As an example, in Kentucky,US, 81% of coal is used to generate electricity. Each of these uses has specific requirements, but generally a high Btu value, and a low sulphur, ash, and moisture content are desirable. The important properties of coal are dependent upon the specific industrial use of the coal. Undesirable chemical constituents in coal such as sulfur, chlorine, sodium, and various hazardous air pollutants may be important for some uses of coal. The washability of a coal is a property that determines how easily these chemical constituents and the ash content of the coal can be reduced through preparation before the coal is used. Important handling properties include grindability, content of scaling agents (chlorine and sodium cause scaling in boilers), and ash fusion. Ash fusion is a property that indicates whether the ash totally melts (low ash fusion) and must be removed from the boiler as a liquid, or forms "clinkers" or cinders (high ash fusion) that must be removed as a solid. Boilers are designed to burn coals with specific ash fusions for this reason.

In the past, coal had a variety of uses. Gas for gas lights was originally made from coal in most cities. In fact in Britain this so-called illuminating gas was made from coal until the 1950's.

Large amounts of coal were once consumed for domestic heating, railroad fuel and for stationery steam engines. In those days coal was often mined near cities and wherever the railroads went. Coal was once a very important source of heat for smelting iron ore for the iron and steel industry, and still is to some degree. In US, Coal is truly America's energy strength. It is to the U.S. what crude oil is to Saudi Arabia.

Industrial Applications: Coal is also used in industrial processes, primarily for steel making and cement manufacturing. Both uses can release air pollutants. The Clean Coal Technology Program demonstrated new ways to use coal directly



in the blast furnaces of steel mills, rather than converting it to coke (the coking process releases pollutants which, unless captured, can become harmful air emissions). Another Clean Coal project tested a new type of scrubber for a cement kiln that used previously discarded dust from the kiln as a chemical to absorb sulphur dioxide and chlorine emissions before they escaped into the atmosphere.

Clean Coal Clean coal or washed coal is produced by a cleaning process (e.g., coal output from a coal wash plant). Generally the coal is washed free of clay, shale and other deleterious substances for transport to users. Thermal Coal Coal used for burning in thermal plants to generate electricity. Thermal coals are generally in the bituminous quality range, having a lower heat content (joules or BTU's British thermal units) than metallurgical coals, but a higher heat content than lower grade coals, such as lignite. Metallurgical Coal (Met Coal) A coal which can be used to produce metallurgical coke which has a high compressive strength at elevated temperatures for use in metallurgical furnaces, not only as fuel, but also to support the weight of the charge (particularly in iron and steel making).

Today, due to competition from other fuels and other sources of energy, coal is used mostly to generate electricity. Concern over environmental quality has led to greater use of low sulphur coal in power plants. This adversely affected production in States with mostly high sulphur coal, but rejuvenated the industry in some States with low sulphur coal.

Nowadays most coal is burnt at powers stations to make electricity.

Most coal mined in the world is burned to make electricity. Most people do not realize that when they use electricity, they are probably also using coal. Of the coal that is not used to make electricity, most is used to make steam for heating, as coke in steel making, or is exported. In developing countries half the world's population depends on coal for heat.

Almost all of the coal consumed in the world is for electric power generation by combusting the coal in boilers and generating steam to power a turbine. Coal is being used to a limited extent in gasification based plants to produce gas to fuel gas turbine based combined cycles (IGCCs) and in some countries such as China for chemicals synthesis. With more advanced gas turbines under development, coal based IGCC will have a strong economic and environmental



basis to compete with boiler based power plants.

An Energy Bargain

Coal is also an energy bargain for the United States. Historically it has been the least expensive fossil fuel available in the country, and in contrast to other primary fuels, its costs are likely to remain stable or decline as mine productivity continues to increase.

During the past decade, in fact, coal prices at U.S. steam electric power plants actually declined about 30%, in nominal terms, while petroleum and natural gas prices increased by 26% and 60%, respectively.

The low cost of coal is a major reason why the United States enjoys some of the lowest electricity rates of any free market economy.

The Nation's Power Workhorse

Because of its abundance and low cost, coal now accounts for more than half of the electricity generated in the United States.

The nation is likely to use more coal in the future, especially as an expanding digital economy creates new demands for electricity. Even with the large projected growth in other power generation fuels - especially natural gas - coal will continue to supply about half the nation's electric power for at least another 20 years. And because of the overall increase in power demand, the nation will likely require that 20 percent MORE coal be used by 2020.

Environmental problems of coal production and burning Combustion

The combustion process provides tremendous amounts of energy from a fuel and this energy is converted or transformed producing heat for cooking, making hot water, or to generate steam for manufacturing or turning a turbine to produce shaft power and electricity, to produce mechanical motion as in an auto engine, or thrust as in an aircraft or shaft power as in a land based engine.

Average Cost of Fossil Fuels Delivered to Utilities, 1999 (Cents per Million Btu)

Coal is America's Major Source of Electricity Generation

Electricity Generation by Fuel, 1999 (Million Kilowatt Hours)



The chemical energy contained in fossil and biomass fuels which is released by the combustion process consists of reactions with oxygen contained in the air. The fuel bound energy is first converted to thermal energy which in turn may be converted to shaft power and motive power in a reciprocating engine (as in automobiles, trucks, busses, locomotives and ships) or in a rotating engine such as a gas turbine or steam turbine or propulsion energy

(as in jet and prop aircraft). The shaft power may also be used to generate electric power which involves turning a generator connected to a reciprocating engine or a gas turbine or a steam turbine. In institutional energy and manufacturing applications where heat energy is required, the combustion process is utilized in boilers and furnaces. Internal combustion engines (diesel engines or gas turbines) in addition to generating electricity may also be used to provide heat energy by recovery of the energy contained in the exhaust gases. Such a dual purpose application is called cogeneration and provides for very efficient utilization of the fuel bound energy. Air conditioning may also be provided from the heat utilizing an adsorption refrigeration cycle such as the lithium bromide cycle for moderate temperature refrigeration or an ammonia absorption cycle for deep refrigeration temperatures. A fuel cell may also be utilized in a cogeneration mode.

Finally, the familiar barbecue is another example of the application of the combustion process.

The combustion of fuels requires the consumption of large quantities of air. For example, 150 Lb of a fuel (oil) requires about 2000 Lb of air and the resulting CO2 introduced into the atmosphere is about 250 Lb. Small quantities of pollutants such as NO, CO and hydrocarbons are also formed, these quantities being negligible from engineering calculations standpoint but very significant from the environmental standpoint.

Combustion Process. The combustion process involves some 1000 reactions to complete the oxidation process forming CO2 and H2O, the ultimate products of combustion. However, pollutants such as CO, HCs, soot, NOx, SO2 are also formed during the combustion process as a result of the various reactions.

Carbon Monoxide (from Natural Gas Combustion). The CH4 molecule is very stable and requires high energy atoms to break loose an H atom forming the CH3 radical which plays a key role in propagating the combustion process. This process includes the partial oxidation of CH4, oxidation of CO, OH reactions and NO formation reactions. CO formation involves a number of steps but is a fast overall reaction while the oxidation of CO to CO2 is very slow and as a result, the auto engine produces significant amounts of CO due to the short residence time. In a gas turbine, however, more residence time is available within the combustor and the CO emissions are much lower. High temperatures and O2

concentrations and large residence times are required for the CO oxidation and involves the reaction with the OH radical formed during the combustion process. High CO emission not only means more pollution but also lower thermal efficiency.



Nitrogen Oxides. The NO is produced from (1) high temperature oxidation of molecular N2 (thermal NO), (2) hydrocarbon radical attack on the molecular N2 (prompt NO), and (3) oxidation of chemically bound nitrogen in the fuel (fuel NO). The thermal NO, i.e., the formation of NO from the N2 present in the combustion air requires the breaking of the covalent triple bond in the N2 and requires very high temperatures and forms by the action of the O radical produced during the combustion process. Increased temperature, residence time, and O2 concentration increase NO emissions which is in direct contrast to the conditions required for CO formation. As much as 60 to 80% of the fuel bound nitrogen present in fuels such as oil and coal forms NO.

The NO formation reaction suddenly takes off around 2800 deg F or 1540 deg C and thus a window of opportunity exists to control NO by staying just below this temperature. Thermal NO formation shows an inverse relationship with respect to HC and CO emissions when the air to fuel ratio is varied. Control strategies include (1) burning under lean conditions, (2) staged combustion with rapid quenching of the flame by the secondary air, (3) pre-mixed burners (ideally, with variable geometry for varying load of the boiler or engine, and (4) flue gas recycle. Post combustion processes are also sometimes applied but have certain disadvantages such as transforming NO into other undesirable species. To meet the ultra low NOx emissions being mandated, the internal structure of the combustion process which is complex and combines fluid dynamics, turbulent mixing, high temperature chemistry and heat transfer need to be understood to develop new solutions without compromising efficiency at full or partial load.

The formation of NO2 is not significant during the combustion process, however the NO oxidizes to NO2 in the atmosphere and thus all NO is potential NO2. NOx refers to NO plus NO2. Another oxide of nitrogen, N2O which is also formed during the combustion has become important in recent years due to its role in the stratosphere as a greenhouse gas. It is formed in significant concentrations (from an environmental impact standpoint) in fluidized bed combustion.

Steam Turbine

A steam turbine based power plant consists of raising high pressure steam in a boiler from the thermal energy and expanding the steam in a turbine to generate shaft power which in turn is converted into electricity in the generator.

Axial flow steam turbines consist of circularly distributed stationary blades called nozzles which direct steam on to rotating blades or buckets mounted radially on a rotating wheel. Typically, the blades are short in proportion to the radius of the wheel, and the nozzles are approximately rectangular in cross section. Several stages of expansions are obtained by using a series of nozzles and buckets, with the exhaust from the buckets of one stage flowing directly into the nozzles of the following stage. A compact machine can be built economically with ten or more stages for optimum use of high pressure steam and vacuum exhaust by mounting the wheels of a number of stages on a single shaft, and supporting the nozzles of all stages from a continuous housing. Large axial turbines must be operated under such conditions that the exhaust steam does not contain more than 10 to 13% of liquid since condensate droplets could seriously erode the high velocity nozzles and blades. The moisture content of the exhaust is dependent upon the inlet steam pressure/temperature



combination. Special moisture removal stages may be incorporated in the design when the steam superheat temperature is limited.

Steam may be utilized directly in the steam turbine without any superheat as may be done with low pressure steam, or superheated to increase the cycle efficiency. Reheat may also be included to further increase the ef ficiency of converting heat to power by superheating the steam after partial expansion and admitting the steam thus reheated back into the turbine.

Coal has a very complex structure and being a solid is more difficult to burn. Coal combustion undergoes devolatilization and combustion of the released gases, char combustion and fly ash formation which are particles 10um in size (the low visibility around certain coal fired power plants is due to the fly ash). Acid mine drainage Subsidence, Global Warming Slag (spoil), heaps Acid rain Clean Coal Technologies

Clean Coal Technologies (CCTs) are defined as 'technologies designed to enhance both the efficiency and the environmental acceptability of coal extraction, preparation and use'. These technologies reduce emissions, reduce waste, and increase the amount of energy gained from each tonne of coal.

Clean coal technologies play a key role in improving coal's environmental acceptability and performance. Ongoing research ensures that advances are continually being made in this area. Improvements in coal combustion efficiency dramatically reduce emissions from coal combustion as the graph below highlights.

Clean coal technologies are a family of new technological innovations that are environmentally superior to the technologies in common use today. Clean coal technologies can be new combustion processes - like fluidized bed combustion and low-NOx burners - that remove pollutants, or prevent them from forming, while the coal burns.

Increasing coal combustion technology efficiency from 35 to 40% reduces carbon dioxide emissions by over 10%.



Clean coal technologies can be new pollution control devices - like advanced scrubbers - that clean pollutants from flue gases before they exit a plant's smokestack.Still other clean coal technologies can convert coal into fuel forms that can be cleaned before being burned. For example, a clean coal plant may convert coal into a gas that has the same environmental characteristics as clean-burning natural gas.

In US, the Clean Coal Technology Program is primarily targeting for innovative technologies in four major technology categories:

Advanced Pollution Controls: These devices could be installed on existing power plants or built into new facilities. Their purpose was to provide more effective and/or lower cost ways to reduce sulphur dioxide and nitrogen emissions. Examples of these devices included:

• SO2 control systems: These devices remove sulfur dioxide pollutants from the combustion gases after they exit the boiler.

• The Clean Coal Technology Program tested two basic versions of this technology:

• One worked inside the existing ductwork of a power plant. These devices are suitable for smaller, older plants with limited space for adding equipment. Typically these devices can reduce sulfur pollutants by 50 to 70%.

• For larger plants with the available space, the Clean Coal Technology Program tested advanced flue gas desulfurization technologies, or scrubbers. These devices are typically built as separate modules and can reduce sulfur pollutants by more than 90%. In the Clean Coal program, the advanced scrubbers were designed to remove the sulphur in an environmentally safe, solid powder rather than the difficult-to-handle sludge of older technologies.

• NOx control technology: These devices reduce emissions of nitrogen oxides (NOx). Three basic categories were tested:

The Pure Air Flue Gas Scrubber reduces SO2

emissions by 95% and produces gypsum, a useable byproduct.



• (1) new combustor designs (low-NOx burners) that retard the formation of nitrogen oxides by carefully controlling the way coal burns. These devices reduce NOx by 37 to 68%;

• (2) "reburning" technology where natural gas or coal is burned above the main combustion zone in such a way that nitrogen oxide pollutants are broken down into harmless molecular nitrogen before they leave the boiler. Reburning can reduce NOx emissions by 50 to 67%; and

• (3) scrubbing systems that inject ammonia or urea into combustion flue gases to remove nitrogen oxide pollutants. Non-catalytic technologies can reduce NOx by 30 to 50% while selective catalytic systems can eliminate 80 to 90%+ of NOx.

Several Clean Coal Technology projects combined both sulphur and nitrogen pollutant controls.

Advanced Power Generation Technologies: These were complete electric power generating systems that offered superior efficiency and environmental performance over conventional coal-burning systems. Four major categories of power generating systems were demonstrated in the Clean Coal Technology Program:

Fluidized Bed Combustion: Fluidized bed combustors remove pollutants inside the boiler - no scrubber or post-combustion sulfur and nitrogen controls are needed.

Rather than burning coal as a blown-in powder, fluidized beds mix pulverized coal with limestone and suspend the mixture on jets of air in a floating "bed" that resembles a boiling fluid. The limestone removes sulfur as it is released from the burning coal and converts it into an environmentally benign powder. The turbulent actions also reduces the temperature of the combustion process below the threshold where large amounts of NOx form. Fluidized bed systems can reduce sulfur dioxide by 90 to 95% and nitrogen oxides by 90% or more.

The Clean Coal Technology Program demonstrated fluidized bed systems that burn coal under atmospheric and pressurized conditions.

B&W's Low-NOx Burneris one of a new class of low-polluting burners being installed on nearly 75% of U.S. coal boilers.

The Nucla Fluidized Bed System helped pioneer fluidized bed technology at utility scale.



• Gasification Combined Cycle: These systems depart from coal combustion altogether. Instead, coal is turned into a gas which can be cleaned of its impurities, virtually to same levels as natural gas. Then the gas is burned in a gas turbine to generate one source of electricity. Exhaust from the gas turbine is hot enough to boil water, creating steam to drive a steam turbine and generate a second source of electricity. This "combined cycle" technology offers a new technological approach for increasing power plant fuel efficiencies. Initial gasification-based plants could boost efficiencies by as much as 20% over conventional coal-burning power plants, and improved versions might eventually double today's efficiencies.

Gasification combined cycle technologies are among the cleanest ways to generate electricity from coal. As much as 95 to 99% of the sulfur and nitrogen impurities in the coal gas can be removed by known chemical processes. These pollutants can be converted into useable products, such as chemicals and fertilizers.

• Coal-Fired Diesel Engine: One Clean Coal Technology project is preparing to test a diesel engine that uses coal-oil or coal-water slurry fuel. The diesel engine would power an electrical generator to produce electricity onsite.

• Slagging Combustor: Another type of clean coal technology is a slagging combustor, so-named because it removes the coal ash as a molten slag in the combustor rather than the boiler. This prevents ash from building up on the furnace walls and degrading the boiler's efficiency. The Clean Coal Technology Program tested slagging combustors for both industrial and utility applications.

Advanced Coal Processing: The Clean Coal Technology Program tested several technologies for changing coal into cleaner forms of fuel.

One of the most successful projects in this category is the Liquid Phase Methanol Process, a process in which coal gas is converted into methanol by bubbling it through a special reaction vessel filled with catalyst particles suspended in a liquid slurry. Methanol can be used as a fuel or as a feedstock for several chemical manufacturing processes.

Other Clean Coal Technology projects examined ways to upgrade low-quality coals, such as those found in the Western U.S., into fuels with much higher heating values. One technology converted coal into both solid and liquid forms, both of which could be burned as clean fuels. Another project developed a personal computer software package that could assist utilities in selecting the optimal quality coal for a specific type of boiler.

TECO's Gasification Power Plant is one of the world's cleanest and most fuel efficient coal plants.



Coal Consumption1 and Recoverable Reserves

The following table shows the coal consumption and the estimated reserves in 1995 in some countries (multiply ST by 0.9072 to obtain MT or Mega Gram):

Country Consumption, 10 ST Reserves, 10 ST

Australia 123 196,630

China 1,464 126,200

Germany 284 26,455

India 327 75,009

Japan 140 886

South Korea 52 202

Mexico 12 1,300

U.S. 941 268,500

TOTAL WORLD 5,117 1,142,968

The Changing face of the U.S. Energy Needs

Year Significant Events

1700's Steam engine powered by wood.

1800's Steam engine powered by coal.

1900's

Oil well drilling. Refinement of crude oil. Internal combustion engine.

1920's Coal provides 80% of the Nation's needs.

~1945 Oil replaces coal except for electrical power generation.

1990's Fossil fuelsd provided 80% of the Nation's energy supply.

Some converted to coke for use in metals smelting. Among the most important resources of an industrial society are those that provide energy - this is what we use to drive machines and use to produce other materials (eg. smelting of metals). For much of history main source of energy (fuel) was wood (technically renewable). Now fuels dominated by fossil fuels (80%) with hydro (5%) nuclear (7%) renewables (5%)



Major Energy Uses for Fossil Fuels

Fuel *Sector.......................Major use

Natural gas

Industrial...................Heating Commerical................Heating Residential.................Heating and cooking

Coal

Industrial...................Electrical power generation and industrial processes

Commerical................Lighting Residential.................Lighting

Oil

All sectors.................Transportation Industrial ..................Heating Residential ................Heating

* Sectors arranged in descending order of magnitude.

Present day breakdown of energy supply in the U.S.

Source Percentage supplied

Oil 44

Natural Gas 25

Coal 23

Nuclear, hydro, and all other sources 12

FORMS OF ENERGY Energy is the capacity to do work, but is present in different forms: kinetic: motion, heat, electricity potential(stored): chemical, nuclear, elastic, gravitational, elecromagnetic Can be converted from one form to another, eg. chemical —> electrical (battery) electrical —> kinetic (electric motor) etc etc. Rate of consumption of energy is called power UNITS OF ENERGY Basic unit of energy in SI (system internationale) is the joule One joule is defined as the energy needed to raise the temperature of one

kilogram of water by 1o C)



Power is the rate of use of energy or energy/time Thus, energy = power x time Basic unit of power - the use of one joule/second is called the watt Other units: Kilowatt-hour (kw-hr)= 1000 watts x 60x60 joules 1 kw-hr= 3.6 x 106 joules Calorie = 4.18 joules 1 kw-hr = 8.6 x 105 calories (note that a dietetic calorie, the type talked about in diets, is really a kilocalorie - that is equal to 1000 calories!) British thermal units (BTU) = 252 calories = 2.93 x 104 kw-hr = 1.053x103 joules

Quad= 1015 BTU = 1.05 x 1018 joules = 2.93 x 1011 kw-hr For coal 1 metric ton coal = 0.66 metric tons of oil = 5 bbl of oil 1 metric ton coal = 2.85 x 1010 joules = 7.95 x 103 kw-hr = 2.7 x 107 BTU For petroleum Oil is measures in barrels (bbl); 1barrel = 42 gallons(US), 7.5 barrels = 1metric ton

1bbl = 5.7 x 109 joules = 1.59 x 103 kw-hr = 5.4 x 106 BTU SPECIFIC ENERGY OF COAL

There are two ways to express the specific energy (SE), the Gross SE and the Net SE. The difference between the two comes from the way in which the water in the coal is treated in the measurement of SE. The normal laboratory measurement for SE will report the Gross SE.

When the coal is burnt, water in the coal is evaporated, and the water which is formed from combustion of the hydrogen in the coal is also evaporated. The heat required for evaporation of this water is the difference between gross and net SE, and the formula to calculate the Net SE from the Gross SE is as follows:



It does not matter which basis (adb, daf, etc) for SE, H2O and H2 are used, as long as they are all the same. However, the net SE is really only relevant for "as received" or "as fired" coal.

For bituminous coals the difference between Net and Gross SE is approximately 1.0 MJ/kg (ar), or 240 kcal/kg (ar).

One Tonne of Coal

Mass Balance

Energy Balance

ENERGY CONSUMPTION PATTERNS Energy is just like the other resources discussed - the richer consume more than the poor. Note that much of this is not just direct consumption, but is the energy invested in the manufacture of articles. US with about 5% of world population consumes about 33% energy. Reserves and Production

Estimated reserves are based on geological probabilities of existing fossil fuels. There is no way to verify these reserves without exploratory drilling.

Proven reserves may increase or decresase with the price of oil. The extent of the reserves is calculated from sinking numerous wells to define the extent of the field.

Production refers to the withdrawal of the fossil fiuel from the field. It generally limited to 10% of the remaining reserves.



When will fossil fuels run out?

Coal

• the U.S. reserves are estimated at 29% of the world's supply. • Estimated to last 150-300 years even with a tripled consumption rate. • Natural gas • Methane reserves to run out sometime between 2025-2050 • LPG (liquid petroleum gas) = propane and butane. • Crude oil • Estimates range from 2010-2050

Sustainable Development - the Role of Coal

Sustainable development has three inter-related pillars: economic, social and environmental. They have equal status and an integrated approach is needed to ensure that all can be met. Sustainable development requires secure and reliable access to affordable energy. For the two billion people who lack it, access to modern energy and in particular to electricity, is essential for generating local industry and employment, alleviating poverty and improving public health.

Coal is an essential element of global sustainable development. It is the world’s most widely available, affordable and secure source of energy.

This section looks at the overall challenge of sustainable development and the contribution coal makes to the three pillars of sustainable development.

Arang Batu - Bahan Api

Kandungan galian dan organan di dalam batu batan menyebabkannya sangat bernilai daripada segi ekonomi. Batu-batan yang boleh digunakan sebagai bahan api ialah gambut, arang batu perang (lignit), bitumen dan arang batu wap, antrasit dan minyak galian. Bahan api ini dijadikan sebagai sumber haba dan tenaga di rumah dan di kilang kilang. Pengkarbonan arang batu menghasilkan arang kok dan gas arang batu. Arang kok digunakan di relau bagas, manakala gas aran batu di unakan di rumah untuk memasak. Arang batu melalui proses pemisahan kimia boleh menghasilkan lebih kurang 200, 000 hasil sampingan seperti tar, minyak wangi, racun rumpai, baja, racun serangga dan bahan letupan. Minyak galian pula menghasilkan petroleum yang sangat penting untuk perusahaan pengangkutan dunia. Plastik adalah hasil sampingan petroleum yang boleh dijadikan berbagai barang kerana ia ringan dan tahan lama.

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